if CPP_SPM had a debug mode: what should it do?

[Remi-Gau]

I'll start:

• make sure verbosity is turned to the max so you can see everything
• make sure it runs in dry_run mode (prepare the batches but do not run them)
• use spm_jobman('interactive', matlabbatch); instead of spm_jobman('run', matlabbatch); to let you explore the batches you are about to run